Natural and Environmental Sciences

Natural and Environmental Sciences 4

UNESCO Science Report: towards 2030

samedi, 12 novembre 2016 12:36 Written by

There are fewer grounds today than in the past to deplore a North–South divide in research and innovation. This is one of the key findings of the UNESCO Science Report: towards 2030 launched on 10 November 2015.

For two decades now, the UNESCO Science Report series has been mapping science, technology and innovation (STI) around the world on a regular basis. Since STI do not evolve in a vacuum, this latest edition summarizes the evolution since 2010 against the backdrop of socio-economic, geopolitical and environmental trends that have helped to shape contemporary STI policy and governance.

Written by about 60 experts who are each covering the country or region from which they hail, the UNESCO Science Report: towards 2030 provides more country-level information than ever before. The trends and developments in science, technology and innovation policy and governance between 2009 and mid-2015 described here provide essential baseline information on the concerns and priorities of countries that should orient the implementation and drive the assessment of the 2030 Agenda for Sustainable Development in the years to come.

The report is available for download (pdf). You can also order a copy.

The Chinese, French, Russian and Spanish editions of the report will be released before the end of 2016 and will be available for consultation and download on this page. The Arabic edition will follow in 2017.

Read the Executive Summary in one of the following nine languages:
English | Français | Español | Русский | العربية | 中文
Português | Deutsch | Catalan

All resources related to the UNESCO Science Report are open access and may therefore be downloaded freely.

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To better understand mega-eruptions, just add water

lundi, 24 octobre 2016 18:08 Written by

Volcanic eruptions bring images of burning lava and ash, not water. A new NASA study has shown, however, that to correctly model the climate effects of an eruption — especially mega-eruptions many times larger than anything in recent history — scientists need to include the atmospheric effects of erupted water vapor.

For a thousand years before the Industrial Revolution, volcanoes were the greatest climate-changing force on Earth. A big eruption in the tropics cools much of the planet by throwing volcanic gases high into the atmosphere, where they change into microscopic particles known as aerosols and spread around the globe, reflecting incoming sunlight. The 1991 eruption of Mt. Pinatubo in the Philippines cooled Earth enough to completely offset the effects of greenhouse-gas-induced warming for about two years. 

Pinatubo was the largest eruption of the last century, but some eruptions of the last millennium are estimated to have been 10 times larger, such as the eruption of the Indonesian volcano Samalas in 1257. In a climate model simulation of the past thousand years, these mega-eruptions are, unsurprisingly, followed by mega-cold spells that reduce global temperatures by 2°F (more than 1°Celsius). But tracers of past climate, such as tree rings and polar ice thousands of years old, tell a different story. These records don't indicate such a drastic, worldwide cooling following mega-eruptions.

The mismatch between eruptions' effects in past climate records and in climate models became widely recognized after a major international study of climate model performance, completed in 2012. “The whole community went back to the drawing board and said, ‘What's going on here?’” said Dr. Allegra LeGrande of NASA's Goddard Institute for Space Studies, New York, lead author of the new study. Research and testing indicated that the problem was likely to center on how processes are represented in the models in a simplified way when they can’t be explicitly represented in their full complexity.

Strong eruptions shoot a complex stew of gases into the atmosphere: sulfur compounds, water vapor, halogens, carbon compounds and others. Atmospheric chemists have learned a great deal about the chemical reactions these gases and aerosols trigger in the atmosphere — and the climate consequences. Until very recently, however, computational technology limited the scientists’ ability to put all of their understanding of volcanic emissions’ chemistry-climate interactions to work in computer simulations. Sulfur compounds, especially sulfur dioxide, are key to post-eruption cooling, so modelers had previously focused on sulfur chemistry. New technology now allows them to see how all the various gaseous emissions — including water in addition to sulfur dioxide — influence climate following a mega-eruption.

The stratosphere is naturally extremely dry. Without erupted water vapor, there wouldn't be enough water in this atmospheric layer for critical reactions with sulfur dioxide to occur. Models that don't track water vapor show sulfur dioxide lingering too long in the stratosphere. Additional water from the volcano speeds up the change of sulfur dioxide gas into sulfate aerosols and also helps the aerosol particles grow bigger more quickly. The size of the aerosols is important because larger particles cause more warming than cooling.

LeGrande and her coauthors simply added erupted water vapor to the NASA Goddard Institute for Space Studies' ModelE climate model. “We did a preliminary set of experiments that kept track of both sulfur and water,” as she explained it. “We showed that water can change the response to the sulfur dioxide injection.” For a Samalas-sized mega-eruption, tracking both sets of compounds reduced the subsequent global cooling by about a factor of three over simulations that did not track water. 

LeGrande notes this study is only one step toward more realistic simulations of eruptions. “We've shown that water is important, but we need a full chemistry picture of what's in the volcanic plume,” she said. “We believe future work will show the importance of other constituents, like ash and halogens. Our goal is to make sure that we have the best toolkit we can have for studying climate, including future volcanic eruptions.”

The study was motivated by a paleoclimate problem, but LeGrande noted that it has implications for the future as well. “If a mega-eruption comes along next year, we’re better prepared than we were two years ago. The whole point of studying paleoclimate is that we want a model that can accurately simulate climate — period.”

Reference

LeGrande, A.N., K. Tsigaridis, and S.E. Bauer, 2016: Role of atmospheric chemistry in the climate impacts of stratospheric volcanic injections. Nature Geosci., 9, no. 9, 652-655, doi:10.1038/ngeo2771.

Source: http://climate.nasa.gov/news/2493/to-better-understand-mega-eruptions-just-add-water/


Historical records may underestimate sea level rise

lundi, 24 octobre 2016 17:52 Written by

A new NASA and university study using NASA satellite data finds that tide gauges — the longest and highest-quality records of historical ocean water levels — may have underestimated the amount of global average sea level rise that occurred during the 20th century.

A research team led by Philip Thompson, associate director of the University of Hawaii Sea Level Center in the School of Ocean and Earth Science and Technology, Manoa, evaluated how various processes that cause sea level to change differently in different places may have affected past measurements. The team also included scientists from NASA’s Jet Propulsion Laboratory, Pasadena, California, and Old Dominion University, Norfolk, Virginia.

“It’s not that there’s something wrong with the instruments or the data,” said Thompson, “but for a variety of reasons, sea level does not change at the same pace everywhere at the same time. As it turns out, our best historical sea level records tend to be located where 20th century sea level rise was most likely less than the true global average.”

One of the key processes the researchers looked at is the effect of “ice melt fingerprints,” which are global patterns of sea level change caused by deviations in Earth’s rotation and local gravity that occur when a large ice mass melts. To determine the unique melt fingerprint for glaciers, ice caps and ice sheets, the team used data from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites on Earth’s changing gravitational field, and a novel modeling tool (developed by study co-author Surendra Adhikari and the JPL team) that simulates how ocean mass is redistributed due to ice melting.

One of the most fascinating and counter-intuitive features of these fingerprints is that sea level drops in the vicinity of a melting glacier, instead of rising as might be expected. The loss of ice mass reduces the glacier’s gravitational influence, causing nearby ocean water to migrate away. But far from the glacier, the water it has added to the ocean causes sea level to rise at a much greater rate.

During the 20th century, the dominant locations of global ice melt were in the Northern Hemisphere. The results of this study showed that many of the highest-quality historical water level records are taken from places where the melt fingerprints of Northern Hemisphere sources result in reduced local sea level change compared to the global average. Furthermore, the scientists found that factors capable of enhancing sea level rise at these locations, such as wind or Southern Hemisphere melt, were not likely to have counteracted the impact of fingerprints from Northern Hemisphere ice melt.

The study concludes it is highly unlikely that global average sea level rose less than 5.5 inches (14 centimeters) during the 20th century. The most likely amount was closer to 6.7 inches (17 centimeters). 

“This is really important, because it provides answers to the question about how melt fingerprints and the influence of wind on ocean circulation affect our ability to estimate past sea level rise,” said Thompson. “These results suggest that our longest records are most likely to underestimate past global mean change and allow us to establish the minimum amount of global sea level rise that could have occurred during the last century.”

Results are published in Geophysical Research Letters. To read the full paper, visit:

http://onlinelibrary.wiley.com/doi/10.1002/2016GL070552/abstract

GRACE is a joint NASA mission with the German Aerospace Center (DLR) and the German Research Center for Geosciences (GFZ), in partnership with the University of Texas at Austin. For more information on the mission, visit:

http://grace.jpl.nasa.gov

http://www.csr.utexas.edu/grace

For more information on sea level change, visit:

http://uhslc.soest.hawaii.edu/

https://sealevel.nasa.gov/

Source: http://climate.nasa.gov/news/2504/historical-records-may-underestimate-sea-level-rise/


COP22 in Marrakech

mercredi, 17 septembre 2014 00:00 Written by

The 22nd Session of the Conference of Parties to the United Nations Framework Convention on Climate Change (COP22) will be held in Marrakech, November 7 to 18, 2016. The COP stands for the "Conference of the Parties.” It is the supreme decision-making body of the United Nations Framework Convention on Climate Change (UNFCCC), opened for signature in 1992 during the Earth Summit in Rio de Janeiro and later entered into force in 1994. Through this instrument, the United Nations has equipped itself with an action framework to fight global warming. On the march towards COP22 After its entry into force in 1994, the UNFCCC Secretariat was established in Geneva.

It was then relocated to Bonn in 1995 following the “First Conference of the Parties” (COP1) in Berlin. Since then, there have been twenty-one COPs, with the most recent one organized in Paris this past December. The next one, COP22 is scheduled to take place in Marrakech, Morocco from November 7 to 18, 2016. The COP was created and put in place in order to structure the efforts of the Parties to the Convention as they address climate change. The COP meets annually to review and assess the implementation of the UNFCCC and any other legal instruments the body adopts with the goal of reducing greenhouse gas emissions and fighting climate change.

These annual UN climate change conferences are commonly referred to as COP. Preserving the environment for the benefit of present and future generations The main objective of the Framework Convention and its related legal instruments are to stabilize the concentration of greenhouse gases in the atmosphere at a level that would prevent "dangerous anthropogenic interference with the climate system." The term "anthropogenic" refers to the effects caused by human activity. The Convention stipulates,"Parties should protect the climate system for the benefit of present and future generations on the basis of equity and in accordance with their common but differentiated responsibilities and respective capabilities." According to the UNFCCC, certain countries are particularly vulnerable to the effects of climate change. For example, Small Island Developing States (SIDS), low-lying coastal areas, arid or semi-arid zones and developing countries with fragile mountainous ecosystems.These areas are subject to extreme weather events such as floods, droughts and desertification, etc.

Parties to the Convention have common but differentiated responsibilities.

During the COP, member States, who have common but differentiated responsibilities, strive to reach agreements on reducing greenhouse gas emissions caused by human activity, assess the evolution of their commitments and review the implementation of the Framework Convention and other legal instruments that the COP adopts. Typically a series of negotiating sessions are carried out beforehand in order to optimize the agenda and discussions. As of today there are 197 Parties to the Convention (196 States and the European Union) including Palestine who joined in March 2016.

Link: http://www.cop22.ma/en


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